The purposes of this double-blind randomized clinical trial are to: 1) test the effectiveness of two arms in preventing chemotherapy (CTX)-induced oral mucositis in persons with cancer who are receiving mucositis-producing CTX agents; 2) test the effectiveness of three arms in treating CTX-induced oral mucositis; and 3) determine the impact of the prevention and treatment arms on direct and indirect indices of CTX-induced oral mucositis morbidity. Theories of physiology/pathophysiology, and self-care provide the conceptual framework. All patients will carry out a nurse-initiated systematic oral hygiene teaching program: PRO-SELF:Mouth Aware (PSMA). Random assignment will occur at two stages: prior to the development of CTX-induced oral mucositis (Stage 1) and with the occurrence of CTX-induced oral mucositis (Stage 2). In Stage 1, 448 outpatients, initiating mucositis-producing CTX, will be followed over 3 cycles of chemotherapy. The 448 patients will be assigned to either A) PSMA + Sterile Water mouthwash B.I.D.; or B) PSMA + Chlorhexidine mouthwash B.I.D. Patients who do not develop oral mucositis will come off study at the completion f the third CTX cycle. Patients who develop CTX-induced oral mucositis anytime during the 3 cycles of CTX (estimated 44%) will be randomized to one of the three arms of Stage 2 and followed for an additional 3 cycles of CTX. The treatment arms include: A2) Salt and Soda, B2) "Magic Mouthwash" [Lidocaine viscous solution, Diphenhydramine hydrochloride, (Benadryl), Aluminum Hydroxide suspension, Maalox.], and C2) Chlorhexidine. All Stage 2 treatment arms include the PSMA. Nineteen referral sites will be used for this study. Morbidity, the dependent variable, will include measures of: the incidence, time to onset, time to heal, severity, and pain of CTX-induced mucositis. In addition, infection and problems with ingestion of food and fluid will be measured. Data will be analyzed using repeated measures multivariate techniques. The study findings will answer important questions on the prevention and treatment of CTX-induced mucositis and related morbidity.